Ridged waveguide hybrid ring circuit



lNVENTORS Fig.3.

C. E. VOGELEY, JR, EI'AL RIDGED WAVEGUIDE HYBRID RING CIRCUIT Filed Sept. 28, 1951 May 27, 1958 Clyde E.Vogeley,Jr., ogid'hoddeus A.0sia|. ATTORNEY United States Patent RIDGED WAVEGUIDE HYBRID RING cmcrur Clyde E. Vogeley, In, and Thaddeus A. Osiai, Pittsburgh, Pa., assignors to Westinghouse Electric tl'crporation, East Pittsburgh, Pa a corporation of E'ennsyivania Application September 28, 1951, Serial No. 248,808

4 Claims. (Cl. 333-11 Our invention relates to conductors for electromagnetic oscillations and more particularly to ridged waveguides. In accordance with the prior art, of which we are aware, a standard waveguide hybrid ring circuit has been built, comprising a section of standard waveguide extending in a circle, so as to form a closed circular path for electromagnetic oscillations. Connected to the Waveguide are four branch waveguides, two of which are spaced 180 apart, or in other words, on opposite sides of the circular path formed by the circular waveguide. The third and fourth branches are connected to the circular waveguide, so as to be spaced 60 geometrical degrees around the circular waveguide from each other and from the first and second branches. The properties of such a waveguide hybrid ring circuit are generally similar to the standard waveguide hybrid junction which comprises four waveguides joined together at a common junction. However, the waveguide hybrid ring circuit for a standard waveguide, as presently employed in the art, has the disadvantage that it is frequency sensitive being a fixed tuned device. The reason that the waveguide hybrid ring circuit now employed in the art is fixed tuned is that the distance between the branches must be a function of the wave length of the oscillations employed in the waveguide, therefore, the length of the circular waveguide is critical for any given frequency.

It is accordingly an object of our invention to provide a waveguide hybrid ring circuit which may be readily tuned.

Another object of our invention is to provide a ridged waveguide hybrid ring circuit.

Still another object of our invention is to provide a new and useful electrical apparatus.

A ridged waveguide, as employed in accordance with the principles of our invention, is a hollow chamber of substantially rectangular cross section and having walls of electrically conducting material. Extending into the interior of the chamber, through a bottom wall, approximately equally distant between the two sides, is a reentrant portion which extends into the waveguide a substantial distance and is continuous along the length of 4 the waveguide. This reentrant portion is usually of rectangular cross section. A ridged waveguide of this type has the advantage over a standard waveguide of having the same overall cross-sectional dimension, and of having a lower cutofi frequency than does a standard waveguide of the same overall cross-sectional dimensions, i. e. the same width and height.

In accordance with our invention, we provide a waveguide hybrid ring circuit comprising a circular ridged waveguide hwing connected thereto four-branch ridged waveguides. The four-branch ridged waveguides are connected to the circular ridged waveguide so as to be capable of supplying energy thereto and deriving energy therefrom. The bottom of the circular ridged waveguide is constructed so as to be adjustable to vary the cross-sectional area inside the circular ridged waveguide. The re entrant portion of the circular ridged waveguide which extends upward into the interior of the waveguide is mounted so as to be movable with respect to the bottom of the circular ridged waveguide. Since the wave length of oscillations in a ridged waveguide is a function of a cross section of the ridged waveguide a ridged waveguide may be adjusted so that the wavelength is constant over a wide range of frequencies.

The novel features which we consider characteristic of our invention are set forth with more particularity in the appended claims. The invention, however, with respect to both the organization and the operation thereof, together with other objects and advantages, may best be understood from the following description of specific embodiments when read in connection with the accompanying drawing in which:

Figure 1 is a showing in section of a ridged waveguide hybrid ring circuit built in accordance with one embodi-.

ment of our invention.

Fig. 2 is a cross-sectional showing of the apparatus shown in Figure 1 taken along the line IIII of Figure 1.

Fig. 3 is a showing in perspective of a ridged waveguide hybrid ring circuit built in accordance with one embodiment of our invention.

In accordance with our invention, we provide an inner cylinder 4 and an outer cylinder 6 of electrically conducting material, the outer cylinder having a diameter substantially greater than the inner cylinder, and the inner cylinder being positioned inside the outer cylinder and extending coaxially therewith so as to provide a cylindrically shaped hollow region between said inner and outer cylinders 4, 6. The inner cylinder 4 is provided with threads 10 on the outside thereof.

A metallic top plate 8 is provided at one end of the cylinders 4, 6 filling the region between the cylinders 4, 6 at that end. A bottom plate 12 is provided for engaging the walls of the inner and outer cylinders 4, 6 and forming, in conjunction with the inner and outer cylinders 4, 6 and the top plate 8, a hollow cavity 14. The bottom plate 12 comprises an inner section 16 and an outer section 18 separated by a ridge member 20 therebetween but linked together rigidly by a plurality of curved rods 22. The bottom plate 12 is provided with threads 24 adapted to engage the threads 10 on the inner cylinder 4 so as to be adjustable with respect thereto.

A ridge member 2% is provided which extends into the interior of the cavity 14 through the bottom plate 12 so as to form, in conjunction with the walls of the inner and outer cylinders 4, 6, the top plate 8 and the bottom plate 12, a circular ridged waveguide. The ridge member 29 is provided with threads which engage the inner section 16 of the bottom plate 12 so that the distance which the ridge 20 extends into the cavity 14 may be adjusted by rotating the ridge member 20 about the inner section 16 of the bottom plate and the inner cylinder 4.

Four holes are provided in the top plate 8 into which are inserted the ends of four-branch ridged Waveguides 26, 28, 3t}, 32. These holes are so positioned as to allow the waveguides to feed energ into the circular waveguide. T he holes in the top plate are positioned so that the first branch waveguide 26 and the second branch waveguide 28 are connected to the circular cavity 14 at opposite sides of that cavity. in other words, the first and second branch guides 26, 23 are connected geometrical degrees apart as measured around the length of the circular waveguide. The third and fourth branches 3t 32 are connected to the circular cavity 1 5 so as to be 60 apart and so that the third branch guide 34) is 60 from the first branch guide 26 and the fourth branch guide 32 is 60 from the second branch guide 28.

In the preferred embodiment of our invention, the length of the circular cavity 14 is equal to 1 /2 times the wave length of oscillations to be employed in the waveover a wide frequency range.

' 32 is therefore equal to /2 Wave length when measured around the cavity in a clockwise direction and one wave lengthwhen measured around the cavity'in a counterclockwise direction. Oscillation entering the first branch 26 andtraveling'in a clockwise direction to the fourth branch 32 will be cancelled by oscillations entering the first branch 26 and traveling in a counterclockwise three tion to the fourth branch 32. No oscillations will, therefore, leave the fourth branch 32 in response to oscillations entering the first branch 26, instead the oscillations entering the first branch 26 will divide equally between the third branch 34) and the second branch 28. h

It may be seen from this explanation that the distances between the branch guides isa function of the wave length of the oscillations to be employed in the guide as measured in the guide. It is, therefore, necessary that as long as the relative positions of the branches remain constant, the wave length measured in the guide must be constant. We have found that by adjusting the location of the bottom plate 12 and the ridge member 20, thewave length of oscillations employed in-the guide may be held constant In other words, if a different frequency isto be employed in a guide from that originally anticipated, an adjustment is made in the positionof the bottom plate and the ridge member so as to cause the wave length in the guide for the new frequency to be the same as the wave length in the guide when the apparatus was originally. adjusted for the original frequency.

Although we have shown and described specific ernbodiments of our invention, we are aware that other modifications thereof are possible. Our invention, therefore, is not to be'restricted except insofar as is necessitated by the prior art and the spirit of the invention.

We claim as our invention:

1. A waveguide hybrid ring circuit. comprising a ridged waveguide extending in a circle, said waveguide having a ridge member which is adjustable, said waveguide having a top plate having four openings therein, and four branch waveguides coupled to said circular ridged wave waveguide having a ridge which is adjustable to vary the distance'which said ridge extends into the interior of the waveguide, said waveguide having a top plate having "2,836,799 ii e four openings therein, a firstra second, a third and a connected sixty degrees from said second, and said fourth therein, a bottom plate adjacent said inner'and said outer' cylinders, so as to form in conjunction with said cylinders and said top plate a closed path waveguide, a cylindrical piece of electrically conducting material fastened to said bottom plate intermediate said inner cylinder and said outer cylinder, extending a substantial distance into the said waveguide so as to form, ,in conjunction with said cylinders, said top plate and said bottom plate, a ridged waveguide, and means for supplying electromagnetic oscillations to said cavity, said means comprising a plurality of ridged waveguides entering said closed path through said openings in said plate, said bottom pla'te being movably connected to said inner and said outer cylinders, so as to be adjustable to vary the size ofsaid waveguide, and said cylindrical piece extending into said waveguide being movably connected to said bottom plate so as to be adjustable to vary the distance which.

said cylindrical piece extends into said waveguide.

4. In combination: a ridged waveguide forming a closed path for electromagnetic oscillations, said ridged waveguide having a ridge which is adjustable to vary the distance which said ridge extends into the interior of the waveguide, said waveguide having a top plate having/four.

from the point on said waveguide at which said first conductor 1s connected, said third conductor being connected sixty degrees from saidsecond," and said fourth being connected sixty degrees from said third, the length of said ridged waveguide being one and one-half times the wavelength of oscillations to be employed in said ridged waveguide.

References Cited in the file of this patent, UNITED STATES PATENT S' 2,422,058 Whinnery June 10, 1947 2,520,220 Neergard Aug. 29, 1950 2,593,183 Rado Apr. 15, 1952 2,634,331 Honda Apr. 7, 1953 OTHER REFERENCES Publication 1, Microwave Transmission Circuits by Ragan, volume 9 of Radiation Laboratory Series,'published by McGraw-Hill in 1948. Page 358 is relied on. (Copy in Div. 69.)

Publication II, Hybrid Circuits for Microwaves by Tyrrell, published in Proceedings of I. .R. 13., November 1947, pp. 1294-1306. (Copy in 178 44-113. 

